CHEMISTRY COMMUNITY

Hello!

I understand that the central atoms in question 3.63 have expanded octets but how do I know how many electrons the central atom has exactly? For example, 3.63b has the element XeF2. I drew the Lewis structure normally and I expected Xe to only have 8 electrons but the solutions manual says Xe has 10 electrons. Is there a way to determine how many electrons an expanded octet would have?

Since Xe has an expanded octet you know it can hold more than 8 electrons. To find how many electrons the expanded octet can hold you should first add up the total number of valence electrons of your compound, then draw your lewis structure as you usually would. You will notice that you are missing electrons from your total valence electrons once you've filled all the octets of the other atoms. Since you know Xe has an expanded octet, you can add the remaining electrons as lone pairs there.